Rotary amplifier



oct. 19, 194s. uw, Q COOK 2,451,921

ROTARY AMPLIFIER Filed Nov. 30, 1944 2 Sheets-Sheet l WITNESSES: INVENTOR w WU/ard a 60o/f.

GM 7W-1 09u22.

A'rroRNEy 'iaienieri @cie 19, i948 ROTARYAMPLIFIEB.

Willard G. Cook, Wilkinsburg, Pa., assignor to Westinghouse Electric Corporation, East Pitts= burgh, Pa., a corporation oi.' Pennsylvania Application November 30, 1944, Serial No. 565,816

l Claims. (Ci. S22- 62.)

My invention relates to amplifying generators of the rotary type for regulating, controlling, measuring and the like purposes where small changes in input energy are to be converted into substantially proportional changes in output energy of considerably larger magnitude.

Such amplifying generators have been used in tandeml or feedback circuits, so as to obtain multi-stage amplication. With the known generators, however, such steppeci=up amplification requires a plurality of' tandem-connected machines, and hence a corresponding number of armatures, bearings and the like parts as well as a correspondingly large space.

lt is an object of my invention to aii'orol multi-stage amplification of high sensitivity and high speed of response by means oi' a single rotary machine of the dynamo type.

Another object, allied to the foregoing, is to `provide an amplifying rotary generator which substantially maintains proportionality between input and output energy over an extremely wide range of control.

Still another object of my invention is to pro vide a generator which combines in itself the regulating and amplifying functions of a plurality of interconnected machines thus considerably reducing the space requirements.

lin order to achieve these objects, and in accordance with my invention, I provide an amplifying direct-current generator with at least two field windings and two appertaining pairs of commutator brushes, and connect one of these field windings with the brushes correlated to the other winding so that one winding is energized by the armature output current controlled by the fiel-d of the other Winding.

According to another feature of my invention,

the two or more tiel-d windings of an amplifying generator, designed and operative as just mentioned, are arranged on diierent ileld poles so that the mutual inductance between these windings is considerably lower than that existing between fleld windings on a common ileld pole.

According to still another feature, my invention involves the provision of two or more magnetiza-ble stator field structures, each carrying at leastl one ileld winding, which are so arranged within a single generator that the flux path in each structure is at least partly separate from that of the other structure or structures.

My invention involves also the provision of self-energized ileld windings, in addition to those aforementioned, in order to introduce compensating or feed-back eil'ects for improving or mod-l 2 lfying the characteristic of the multi-stage Inachine.

These and other objects and features of my invention will be apparent from the following description of the embodiments illustrated in the drawings, in which:

Figure l shows diagrammaticallyan amplitying generator according to the invention, operating es a double-stage amplifier;

Figs. 2, 3 and 4 show diagrammatically three further modifications, respectively, of double stage amplifying machines according to the invention;

Fig. 5 is a diagrammatic representation of a generator designed as a triple-stage amplier;

Fig. 6 represents schemsticaily an axial section of still another embodiment of the invention, also operating as a multiple-stage amplifier; and

Fig. 7 shows the circuit diagram of s, closedcycle control or regulating system, in which an amplifying generator according to the invention is used for regulating and controlling the opera tion of a main generator.

Referring to Fig. l, the illustrated direct-current generator has its magnetic stator or frame structure F provided with four eld poles denoted by Pi, P2, P3 and P5, respectively. Each pole carries a ileld winding Wi, W2, W3. or W4. Windings Wiand W2 are connected to input ter-- minals Ai and A2 and represent the control coils oi the amplifying machine. The commutator of the machine is provided with two pairs of contact brushes Bl, B2 and B3, Bt, respectively. Brushes Bi and B2 have an angular position correlated to poles PI and P2 for carrying the armature output current controlled by windingsv Wi and W2. windings W3 and WG are connected to brushes Bi and B2 and hence are energized by that output current. Brushes B3 and B4 have the proper angular position relative to. poles P3 and P4 for deriving the armature out-` pu't current controlled by windings Wl and W4. The output terminals of the machine Ci and C2 are connected to brushes Ci and C2, respectively.

When the armature of the machine is rotating,

small input current traversing the windings WI and W2 causes an amplified current to issue from brushes BI and B2, and to energize-the second pair of windings -WI and W4. This, in turn, causes a still further amplified current to Dass from brushes B3 and B4 through terminals CI and C2 to the load circuit (not shown) atttached between these terminals. In order to achieve substantial proportionality between changes in assassin input and output energy, the magnetic system of the machine operates normally on the unsaturated straight portion of its magnetic characteristic and is normally driven at constant speed.

It will be understood that the customary interpole and compensating windings may be addedfor improving commutating conditions or correcting or modifying the behavior of the machine. One way'of obtaining such a. modication is to equip the machine with self-energized windings as exemplied by the embodiment represented inFig. 2.

The generator according to Fig. 2 is a double stage amplier similar to that of Fig. 1 except that poles PI and P2 are provided with additional windings SI and S2 which are connected across the output brushes B3 and B4 or across terminals CI and C2. Such self-energized windings may be rated and connected for increasing the amplification factor or for compensating purposes. For instance, the energization or windings SI and S2 may be in such a direction and proportion as to counteract or neutralize. the ei'fect of the magnetic linkage between the two sets of poles thereby reducing or substantially eliminating any loss in ampliilcation due to such linkage. j

An increase in ampliilcation can also be obtained by separating the two sets of pole structures magnetically from each other, for instance, in the' manner shown in Fig. 3. The iron frame F of this machine is lined lby a non-magnetic shim N which carries two separate pole structures D and E. Structure D has two poles Pi and P2, and structure E has poles P2 and PI. The four poles are provided with field windings WI, W2, W2, Wl, SI and S2 similar to tl'iose shown in Fig. 2. The appertaining two pairs 'of commutator brushes are denoted by BI,.B2 and B3, B4, respectively.

Another modification of similar type is represented in Fig. 4.. The stator frame G of this machine consists of non-magnetic material such as aluminum and carries two separate magnetic held structures H and K which are provided with the pole pairs PI, P2 and P3, respectively. The ileld poles have pole shoes, which within each pair, extend toward each other so that the distance between the .pole surfaces of each structure H or K is smaller than the distance of each structure from the other structure.

Referring to the embodiments of Figs. 3 and 4,

I the two magnetic held structures (such as H and Kin Fig. 4) consists preferably of a materialof high permeability and low remanence, for instance of the magnetically soft material known I under the trade-name Hypernik. The structures are laminated and rated for operation on the straight portion of their magnetic characteristic so that, when the machine is running at substantially constant speed, the generator output,

appearing across terminals C i and C2 changes substantially in linear proportion to the input signal impressed on terminals Ai andI A2. Due to the 4fact that the magnetic ilux path within each of the two magnetic held structures is substantially free of inductive coupling with the other magnetic structure. a machine of this type aifords an extremely high amplification ratio and an especially high rate of response.

It will be understood from the foregoing that a the invention is not limited to double-stage ampliiiers, but can also be embodied in dynamos for a larger number of amplifying stages. This is vexemplied by the generator shown in Fig. 5.

The rotary amplier, according vto Fig. 5 has three magnetic eld structures L, M and O mounted on a non-magnetic frame G and acting on a single armature. The eld structure L is provided with two poles Pi and P2 which carry held windings Wi and Wt. These windings are connected to input terminals Ai and A2. The appertaining pair of brushes of the commutator are denoted by Bi and B2. Field structure M has two poles Pil and Pf3, 'andcarries held windings W2 and W6 which are connected to the brushes Bi and B2. `The brushes relating to field structure M are denoted by B3 and Bl. Field structure O has two poles P6 and P3 associated with field windings W5 and WG which are connected between the brushes Bil and B5. Two further brushes B5 and B6 appertain to eld structure O and serve to carry the output energy of the last ampliiier stage. Two output terminals Ci and C2 are connected to the brushes B5 and Bti.

The three magnetic fluxl paths extending through the stationary ileld structures L, M and O are magnetically separate from one another t0 such an extent that nearly maximum triple-stage amplification i's obtained between the input -terminals Ai, A2 and the output'terminals CI and C2.

According to Fig. 8, the amature Q and the non-magnetic lframe or ycasing G of the illustrated generator are of elongated shape. Two iield structures H and K. for instance according to Fig. 4, are mounted on the frame G and have each two poles of which only one. denoted by Pi and PI, respectively, is visible in the illustration. The two field structures are axially displaced from each other, so that their mutual inductance is negligible.

It should be understood that, in addition to the field windings described in the foregoing, a machine according to the invention may also be equipped with further windings for providing special control or regulating eiects. For instance, the eld structure representing the input stage of the amplifier may be provided with a plurality of control windings, so that the magnetization of the eld structure is dependent on the nesultant ampere turns of all these windings. An embodiment of such type is illustrated in Fig. 7, in connection with a circuit exemplifying how a generator according to the invention may be used for control and regulating purposes.

The system represented by Fig. 7 contains a main generator MG for producing a direct-current of regulated voltage. The armature l of the main generator MG is connected to the mains 2 and 3 of the output or load circuit. The armature l is driven by a constant-speed motor l. The armature voltage is controlled by a ileld winding l of generator MG which obtains its excitation from a control -generator CG. This control generator is designed and operative in accordance with the present invention. The armature 8 of the control generator is mounted on the shaftv of the main generator MG and hence rotates also at constant speed. The generator CG has four field windings denoted by 7, 8, 9 and i0. Windings l and 8 are mounted on one of the two pole pairs, while windings 9 and I0 are disposed on the second pole pair of the generator. Windings 9 and I0 are connected in parallel to the pair of brushes which carries the output energy controlled by the two windings 1 and 8. The second pair of brushes is connected to field winding 5 of main generator MG in order to supply thereto voltage transformer I3 from an alternating-curil is so rated that it balances the voltage across mains 2 and I during the steady state operating condition of the system so that winding 1 is not energized as long as the steady condition persists. The control circuitoi' field winding 1 contains also the secondary windings of two damping transformers I5 and I6. The primaries of these transformers are connected across the output brushes of the first amplifier stage of generator CG and across the field winding l of the main generator MG, respectively.

Field winding 8 of generator CG is connected to a rheostat i1 which, in turn, is traversed by a constant direct-current derived from a rectifier I8 which is connected through another constant voltage transformer I9 to the alternating-current line i4.

During the operation of the system, the output I voltage of control generator CG is mainly governed by the selected excitation of field winding I, and this excitation is determined by the setting of rheostat I1. As long as the output voltage of the main generator corresponds to this setting. no regulating effect is produced by field winding 1 because the line voltage is fully balanced by the standard voltage appearing across rheostat I I. In order to calibrate this rheostat for each setting of rheostat i1, the sliders of both rheostats are adjusted simultaneously in a given relation to each other, for instance, by means of a transmission, as schematically indicated by the broken line 20, interconnecting the two slid- When the voltage across mains 2 and I changes for instance due to a load variation, this change causes a differential voltage to appear across winding 1. As a result, the winding 1 exerts a regulating effect on the 'control generator of the magnitude and direction necessary to restore the main generator output voltage to its desired value.'

If under certain operating conditions the system may tend to overshoot the desired voltage value, and hence start hunting, such hunting can be prevented by the addition of above-mentioned damping transformers l5 and IB. Both transformers do not afi'ect the steady state operation of the system because no voltage is induced in their secondaries as long as the output voltage of the main generator maintains the desired value. However, as soon as the control generator CG responds to changes in main generator output voltage, an impulse is induced in the secondarles of the transformers in such a direction as to re'- duce the tendency to overshoot. If the two amplifier stages embodied in the control generator are substantially separate from each other in inductive respect, the damping eect of such transformers is highly effective. It will be understood, however, that depending upon the conditions of the particular control system, generators according to the invention need not necessarily bc provided with such damping transformers, or that only one of the damping transformers may be sumcient.

In view of the different modifications described in the foregoing, it will be obvious to those skilled in the art that rotary amplifiers according to the invention can be modified in various respects without departure from the essential features of the invention as set forth in the claims annexed hereto.

I claim as my invention:

l. An amplifying generator comprising an arv mature and a plurality of field structures each having poles of different respective polarities for passing magnetic flux through said armature, said structures being displaced relative to each other, so that the magnetic flux path in each of them is substantially separate from that in said other structures, separate field windings on said structures respectively, and a pair of brushes pertaining to one of said neld structures and connected with said field winding of another structure for obtaining plural-stage amplification.

2. An amplifying generator comprising an armature and a plurality of field structures each having two magnetically interconnected poles of dinerent respective polarities for passing magnetic flux through said armature. said structures being angularly displaced relative to each other, so that the flux path in each of them is substantially self-contained therein, field windings on said structures respectively, and a pair of brushes pertaining to one of said structures and connected with the field windings of another structure for obtaining plural-stage amplincation.

3. An amplifying generator comprising a rotary armature, a non-magnetic frame coaxial with said armature, a plurality of field structures mounted on said frame and each having a pair of magnetically interconnected poles for passing magnetic flux through said armature, said structures being substantially separate from one another, so that the magnetic flux path of each of them is substantially fully contained therein, field windings on said structures, anda pair of brushes pertaining to one of said structures and connected with the field winding of another structure for obtaining plural-stage amplification.

4. An amplifying generator comprising 'an armature and a plurality of field structures each having poles for passing magnetic ux through said armature, said structures being displaced relative to each other, so that the magnetic flux 'path in each of them is substantially separate from that in said other structures, said poles of each structure having their armature ends extended toward each other, so that the distance of each pole from the appertaining other pole of said structure-is smaller than the distance between poles of different structures, field windings on said structures respectively, and a pair of v brushes pertaining to one of said structures and connected with the field winding of another structure for obtaining plural-stage amplification.

5. An amplifying generator comprisin'g an armature and a plurality of field structures each having two magnetically interconnected poles for passing magnetic flux through said armature, said structures being angularly and axially displaced relative to each other, so that the flux path in each of them is substantially self-contained therein, field windings on said structures respectively, and a pair of brushes pertaining to one of said structures and connected.with the field winding of another structure for obtaining pluralstage amplification.

6. An amplifying generator comprising an armature, a plurality of field structures each having magnetically interconnected poles for passing magnetic flux through said armature, said strucy. BRIS.

7. Anamplifying generator comprising a non. ymagnetic frame and an armature coaxial there- "with, two field structures mounted on said frame and angularly displaced relative to each other, each of said structures having two magnetically interconnected poles, field windings disposed on said structures respectively, two pairs of armature brushes located relative to said brushes -to carry the armature output currents corresponding to said structures respectively, input terminals for said field winding of one of said structures, said pair of brushes pertaining to said one structure being connected to the eld winding o! said other structure, and output terminals con-A` nected to said other pair of brushes.

8. A direct-current generator comprising an armature having a .commutator, a plurality of field structures each having magnetically interconnected poles for passing magnetic ux through said armature, said structures being angularly displaced from each other, so that the flux paths in-said respective structures are substantially separate from one another, a plurality of field windings disposed on one of said structures, so that its magnetization is due to the resultant eii'ect of said windings, another eld winding disposed on, another field structure, a plurality of pairs of contact brushes engaging-said commutator and pertaining to Isaid respective field structures, said other eld winding being connected to the pair of brushes pertaining to said one structure.

9. An amplifying generator,` comprising an unsaturated ileld structure provided with a plurality of pole pairs and an amature having a commutator with a plurality of pairs of brushes' correlated to said ,respective pole pairs, control winding means disposed on a iirst one of said pole pairs, terminals connected to said control winding means for providing control excitation, ield windings disposed on a second one oi said pole pairs and connected across the one of said brush pairs which is correlated to said rst pole pair so that said eld windings are energized by voltage generated in said armature under control by said control winding means for causing said armature to generate amplified output volt y age between a pair oi' said brushes that is correlated to said second field poles, an' output circuit connected to said latter pair of brushes, and a feed-back iield winding connected with said output circuit and disposed on the poles of at least one of said pole pairs. l

10. An amplifying generator comprising an unsaturated eld structure provided with a plurality of pole pairs and an armature having a commutator with a plurality of pairs of lbrushes correlated to said respective pole pairs, control winding means disposed on a rst one of said pole pairs, input terminals connected to said control winding means for providing control excitation, field windings disposed on a second one of said pole pairs and connected across the one of said brush pairs which is correlated to said rst pole pair so that said field windings are energized by voltage` generated in said armature under' control by said control winding means for causing said armature to generate amplified output voltage between a pair of said brushes that is correlated to said second eld poles, output terminals connected to said latter pair of brushes, and a feed-back field winding connected across said output terminals and disposed on saidrst pole pair.

. WILLARD G.- COOK.

`REFERENCES CITED The following .references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 931,336 Osnos Aug. 17, 1909 2,000,699 Harding May 7, 1935 

